Method for compacting thermoplastic film material and apparatus therefor

ABSTRACT

There is disclosed a method for compacting thermoplastic film material usually waste film material presenting a rather bulky appearance due to incorporation of air pockets. The waste film is oftentimes in the form of thermoplastic bags of fairly heavy gauge and of fairly large size. The bag is usually the result of use as a means to enclose a stack of a plurality of boxes which have been positioned on a pallet. The bag has been removed and discarded. It is accumulated in a receptacle of relatively large size. The receptacle is constructed of open mesh work on all sides and bottom and possesses a size approximating an area dimension of a pallet and a conventional height of a stack of boxes on such a pallet. The receptacle when loaded with a plurality of the bags is subjected to a heat treatment in an oven which surrounds the receptacle along its sides and top while the receptacle is on the floor, for instance. The oven employed is essentially a housing having an open bottom with a plurality of electric heating elements positioned internally with respect to the inner walls thereof. The oven is relatively movable to encompass the bag containing receptacle. The bags are melted or fused within the receptacle during its dwell time in the confines of the oven. To prevent sticking of the bags to any of the surfaces of the receptacle, at least the inside of the receptacle is given a coating treatment with a plastic release material for instance.

United States Patent 1 1 Tulkoff [451 Aug. 27, 1974 [76] Inventor:Martin J. Tulkoff, 1020 East Lomard St., Baltimore, Md. 21202 22 Filed:Mar. 26, 1973 [21] Appl. No.: 344,624

[52] US. Cl 53/24, 53/25, 53/127,

219/385 [51] Int. Cl. B651) 1/24 [58] Field of Search 219/385, 354, 388,406,

219/521, 535; 53/27, 29, 30, 184, 24, 25, 127; 100/38, 93 P; 264/D1G. 69

[56] References Cited UNITED STATES PATENTS 2,741,009 4/1956 Slayter eta1 53/127 X 3,012,125 12/1961 Woolhouse 219/385 3,214,798 11/1965 Cook100/38 X 3,283,469 11/1966 McBrady et a1. 53/184 X 3,312,811 4/1967Shanklin 219/388 3,581,458 6/1971 Gustavsson 53/30 3,589,102 6/1971Zelnick 53/184 3,662,512 5/1972 Zelnick .53/30 3,702,920 11/1972 Taylor219/521 X 3,723,708 3/1973 Tulkoff 219/385 3,745,915 7/1973 Rehm 53/25 XPrimary Examiner-Travis S. McGehee Attorney, Agent, or FirmEric P.Schellin; Martin P. Hoffman 1 1 ABSTRACT There is disclosed a method forcompacting thermoplastic film material usually waste film materialpresenting a rather bulky appearance due to incorporation of airpockets. The waste film is oftentimes in the form of thermoplastic bagsof fairly heavy gauge and of fairly large size. The bag is usually theresult of use as a means to enclose a stack of a plurality of boxeswhich have been positioned on a pallet. The bag has been removed anddiscarded. It is accumulated in a receptacle of relatively large size.The receptacle is constructed of open mesh work on all sides and bottomand possesses a size approximating an area dimension of a pallet and aconventional height of a stack of boxes on such a pallet. The receptaclewhen loaded with a plurality of the bags is subjected to a heattreatment in an oven which surrounds the receptacle along its sides andtop while the receptacle is on the floor, for instance. The ovenemployed is essentially a housing having an open bottom with a pluralityof electric heating elements positioned internally with respect to theinner walls thereof. The oven is relatively movable to encompass the bagcontaining receptacle. The bags are melted or fused within thereceptacle during its dwell time in the confines of the oven. To preventsticking of the bags to any of the surfaces of the receptacle, at leastthe inside of the receptacle is given a coating treatment with a plasticrelease material for instance.

4 Claims, 13 Drawing Figures 'v MYM o. I

PATENTEDAUEZTISH SHEET 1 BF 4 FIG.

METHOD FOR COMPACTING THERMOPLASTIC FILM MATERIAL AND APPARATUS THEREFORBACKGROUND OF THE INVENTION Thermoplastic film material is being used toa great degree as covering material for packaging small and large itemsof commerce. Large sheets of solid waste plastic film material have beenposing a real disposal problem. The large sheets are difficult tocompress into a mangeable shape as large sheets tend to possess pocketsof air as they are folded or bunched into a trash receptacle. It isquite easy thereby to rapidly fill a trash receptacle with only a fewsheets of relatively heavy gauge thermoplastic film material. The trashreceptacle has the bulk but not the weight.

The use of thermoplastic film material has become even more widespreadwith the advent of the use of bags of such material which are used toencompass a stack of boxes, for instance, on a pallet. The bag isutilized in an upside-down manner and is subjected to heat treatment tothereby heat shrink the bag rather form fittingly about the stack ofboxes. Numerous recently issued US. patents have dwelt with this subjectat great length. Copending US. Pat. application Ser. No. 254,548 filedMay 18, 1972, now US. Pat. No.

. 3,723,708 teaches the concept of employing just such an oven which ismoved vertically to enclose a loaded pallet having a heat shrinkableplastic bag thereon to thereby shrink the bag about the load. The soloaded encompassed pallet is transported to its final destination, atwhich point the bag is removed as by tearing it off. Such bags nowconstitute bulky light trash which is difficult to dispose. Thementioned US. Pat. No. 3,723,708 is herewith incorporated by reference.Certain improvements have been made over the oven disclosed inapplication Ser. No. 254,548; these improve ments have been disclosedand claimed in a US. patent application Ser. No. 344,774 filed Mar. 26,I973 entitled: Improved Apparatus for Heat Shrinking Material About aLoaded Pallet, herewith incorporated by reference.

SUMMARY OF THE INVENTION As thermoplastic film in either sheetform ortorn bags has become an ever greater problem, the present invention hassolved the dilemma by arranging to compact such trash material byemploying compaction by heat. In carrying out the invention the trashplastic material is loaded into a receptacle. The receptacle has sides,ends and a bottom of open mesh material to permit the flow of heat andinfrared radiation into the interior of the receptacle. The receptaclemay also have a closure at its top, also of open mesh material. Thereceptacle has the area size of a conventional pallet and is raised in asimilar manner by conventional skids or casters. The height of thereceptacle is about the size of the height presented by a pallet havinga load thereon normally encompassed by a thermoplastic bag. Thereceptacle may have one of many embodiments hereinafter discussed anddisclosed at considerable length. The receptacle is filled with bags toa level which may be higher than its uppermost leading edge. Thereceptacle is then positioned so as to be enclosed in a unique oven asdisclosed and taught in the US. Pat.

No. 3,723,708 and further described hereinafter. Suffice it to say atthis juncture that the oven has solid insulated sides and likewiseinsulated top. The oven is open at the bottom. Electric heating elementsare positioned interiorly of the ends and sides of the oven, therebyproviding a captured heated ambient. The oven is relatively movable withrespect to the filled receptacle. Means may be located in the ceiling tocompress the bags to a degree so that they are held below the edge ofthe receptacle when the oven is placed over the receptacle. The bags arefused or melted into a much smaller amorphous mass than was presentbefore the heating step. As a result of the melting of the bags to amuch smaller mass, the receptacle is given additional room for morewaste torn bags. The receptacle is cycled again and again to a heattreatment during which more and more bags are melted into a solid mass.The receptacle in at least some of the embodiments are provided withmeans for access to the receptacle to empty it out when desired. Alsothe receptacle is treated with a material which inhibits the sticking ofthe melted bags to the bottom or sides of the receptacle.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of oneembodiment of the receptacle for carrying out the practice of thepresent invention.

FIG. 2 is a perspective view of the arrangement including the oven ofthe present invention illustrating the operation thereof.

FIG. 3 is a cross-sectional view taken along line 33 of FIG. 2.

FIG. 4 is a side view similar to FIG. 3 with a portion broken away.

FIG. 5 is a cross-sectional view taken along line 55 of FIG. 3.

FIG. 6 is an enlarged fragmentary view taken in cross section showing acorner of the receptacle and of the heating oven, respectively.

FIG. 7 is the same cross-sectional view of FIG. 3 wherein the oven is inheating position.

FIG. 8 is a perspective view of another embodiment of the receptacle ofthe present invention.

FIG. 9 is a side view of a group of nested receptacles of the presentinvention.

FIG. 10 is a perspective view of another embodiment of the receptacle ofthe present invention.

FIG. 11 is a perspective view of another embodiment of the receptacle ofthe present invention in a blank condition.

FIG. 12 is a side elevation of the embodiment of FIG. 11 wherein aplurality are stacked one above the other.

FIG. 13 is a fragmentary cross-sectional view of a portion of theapertured material of an embodiment taken along line 13-13 of FIG. 1.

DETAILED CONSIDERATION OF THE INVENTION Now, turning to the drawings fora detailed consideration of the invention, attention is initiallydirected to FIG. 1. It will be noted therefrom that the figureillustrates a rectangularly shaped receptacle ll. The receptacle has abottom, not shown, end walls 12 and side walls 13. The receptaclepossesses skids 14 of the type normally employed on a pallet. The bottomand walls are constructed of a material providing a multiplicity ofopenings so that there is easy communication between the outside andinteriorly of the receptacle.

The receptacle in the embodiment shown has hinged doors and 16 for thetop of the receptacle. Each hinged door comprises one half of the top.The material of construction is similar to the other parts, namely,having a plurality of apertures.

In the embodiment shown the forwardly facing end wall 12 constitutes agate which swings outwardly horizontally on hinges 17. It is latched bya fastening means 18 at one corner of the receptacle. The fasteningmeans may be a hasp, for instance.

The FIG. 1 embodiment is constructed of a grid of wire 20 which issecured to a rectangularly shaped frame constructed of tubular metal 19,for instance. The tubular metal is employed whenever the grid 20 doesnot possess sufficient strength to be selfsupporting. In place of thetubular metal, angle iron may be employed. The hinges 17 may be attachedto the frame at the corner by means of bolts, rivets or welding, forinstance. Similarly, the latch may be attached at the other side of thegate by suitable means.

While not shown the receptacle may have suitable braces or cross piecesas a means of giving more rigidity should it be required. The need foradditional rigidity depends to a large measure on the thickness of thegrid employed.

Similarly, top hinged doors l5 and 16 have their re spective hingessecured to the top of the frame by suitable means. The doors may hangloosely as shown prior to introducing the thermoplastic bags that are tobe compacted. The doors are then closed by merely rotating them in thedirection of the arrows as shown in FIG. 1.

It is contemplated within the purview of the invention that the gridemployed in sides, end walls, top door or doors and bottom beconstructed of one of many materials and may take the form of a varietyof construction. For instance, the grid may be fabricated from wovenwires to produce a pattern of open squares or rectangles. The grid maybe fabricated of woven wires to produce a pattern of diamonds as shown,generally, in FIG. 1. The grid may be constructed of conventionallyavailable expanded metal. The grid may also be constructed of what iscommonly referred to as cyclone fencing. The grid may also beconstructed of sheet metal having apertures cut thereinto. The grid mayalso be constructed of a series of thin strips to produce a grid whichis secured as by welding, for instance. It will be appreciated that manyother manner and forms will come to mind as being applicable in carryingout the present invention.

As has been previously stated, the receptacle 11 or container is to beloaded with thermoplastic bags. The thusly loaded receptacle issubjected to a heat treatment which essentially softens the bags to asufficient degree to collapse them into a relatively small heap. It hasbeen found that the thermoplastic material when softened has an affinityfor the metal surfaces of the receptacle so that it will adhere thereto.To avoid adhesion the metal surfaces coming in contact with thethermoplastic bags are coated with a release material. The materialapplied may be a permanently applied plastic coating such aspolytetrafluoroethylene such as Teflon or a polyester such as Dieldrin.FIG. 13 is illustrative of a grid constructed of wire 20 having acoating 21 of a polytetrafluoroethylene. The plastic coating so appliedprovides excellentv release properties. On the other hand, it has alsobeen found desirable to provide a sprayed-on release coating prior touse of the receptacle. FIG. 8 depicts just such an operation. It will beobserved that a conduit 22 extends downwardly into a receptacle, ofanother embodiment. The conduit terminates in a nozzle 23 adapted tospray a liquid release agent which is either a mineral oil, organicanimal fat or any silicone oil. It is also contemplated that the releaseagent may be applied from an aerosol container under pressure by any oneof a number of conventional means well known in the art.

Before discussing some of the other embodiments of the type ofreceptacle within the consideration of the present invention, it appearsappropriate to further elucidate at this point the manner of use of thereceptacle already discussed. As heretofore disclosed the receptacle isused to contain a plurality of thermoplastic bags of fairly heavy gaugethermoplastic film material. These bags constitute waste or refuse. Theyare the result of removal from pallets containing a plurality of stackedboxes which have been covered with the thermoplastic film usually in bagform.

After the receptacle has been filled with such bags, the doors areoperated to enclose the receptacle. Usually, the bags are quitecumbersome being filled with pockets of air. The receptacle isdimensioned so that it has the approximate size of a conventional palletloaded with a plurality of boxes. By being placed on skids 14 as shownin the embodiment of FIG. 1, the empty or filled receptacle may be movedabout by means of a conventional forklift truck. When the receptacle isfilled as in FIG. 1, the forklift truck is employed to move the filledreceptacle to a position beneath an open bottomed vertically movableoven 30 of the type illustrated in copending application Ser. No.254,548 filed May 18, 1972, now U.S. Pat. No. 3,723,708. FIGS. 2 and 3clearly illustrate such an oven.

The oven 30 has side walls 31 and end walls 32. A top 33 completes theoven. It does not possess a bottom as this would defeat its uniqueutilizability. The walls and top are constructed of sheet metal, forinstance. Preferably, the construction as clearly shown in FIG. 3, is ofthe sandwich type with outer and inner lamina of sheet metal and a coreof suitable insulation material, such as asbestos.

Inside each of the inner end walls 32 is an elongated electric element34, shown by dotted lines. The ele- I ment 34 is positioned along thelower portion of the wall. The longest dimension of the heating elementis such that it bridges a major portion of the width of the end wall.Further, inside each of the side walls 31 are two elongated electricheating elements 35 also shown by dotted lines in FIG. 1. Two of theheating elements 35 are positioned in approximately the same horizontalplane as the heating elements 34 of the end walls 32. Each of the otherheating elements are secured to the inner side wall at the upper portionthereof. The heating elements 35 on each side wall are parallel to oneanother. Additionally, they are of a length so that each bridges a majorportion of the width of the side wall 31.

From FIG. 2 it will be seen that a receptacle 11 having a plurality ofempty used thermoplastic bags therein has been located on the floor 36by a forklift means 37,

(shown in a broken manner) to a control station 40 having suitableelectric switches for starting and stopping the operation of the hoist38. The electric hoist has suitable sensing switches designed to stopthe operation when the oven is in its uppermost raised position and whenit has come to its lowermost position, that is, when it has come to reston the floor 36, for instance. Switches are also at the control stationfor reversing the movement of the oven either at the end of theuppermost position or at the lowermost position or at any intermediateposition. Additionally, the control station possesses a selective timerdevice whereby the period of time when the oven is in the lowermostposition can be controlled by presetting the time. The control stamately250F. A thermostatically operated switch 41 is located in the housing tocontrol a desirable preselected temperature level. The electricity issupplied to the heating elements by a flexible conduit 42 shown infragmentary form.

In FIG. 2 the oven is shown in partial ascent or descent. However, inFIG. 4, the housing has descended so that it rests on the floor 36thereby completely enclosing the loaded receptacle. It has been foundthat with a preset temperature of about 250F, and heating elementsdrawing about 10.6 KW, a dwell time of ID to minutes is sufficient tobring the load to a temperature which enables it to be melted into anamorphous mass. FIG. 3 depicts the oven, in cross section, in acompletely raised position.

For greater assurance that the oven descends in the exact same verticalplane on every occasion, vertical guide upright 43 is provided as moresuccinctly seen from FIGS. 3, 4 and 5. The upright is seen to be an I-beam which may also structurally help to support the ceiling of abuilding. A carriage 44 is designed to ride on the four leading edges ofthe support as can be seen from FIG. 5. With regard thereto the carriage44 has, generally, a U-shaped frame 45 with the end portion of the legs46 and 47 secured, as by welding, for instance, to a side wall 31 of theoven 30. The inner portions of the legs 46 and 47 have extension means48 which have journalling means for one end of an axle 49. The other endis suitably journalled at the apex portion of the frame. The axles 49have journalled thereon wheels 50 which are adapted to ride on the edgesof the upright 43. By accurately controlling the movement of the oven30, suitable markings may be made on the floor to delineate the area inwhich the receptacle is to be positioned. Several color coded markingsmay be made to accommodate various sizes of pallets.

FIG. 3 illustrates the oven 30 in a raised position over a positionedreceptacle having a plurality of bags loaded therein. In FIG. 4 the ovenhas been lowered and the loaded receptacle is being subjected to heattreatment.

FIG. 6 shows an enlarged cross-sectional view of the oven with theheating element to show the concave heat reflector 51 therebehind. Theheat reflector 51 is constructed of an elongated concave sheet metal andis positioned to direct the reflected heat rays in a general upwarddirection in the direction of the receptacle as shown. With regard tothe heating elements secured to the upper portion of the side walls 31,the reflectors are positioned to direct the raysin a somewhat downwarddirection. It will be seen that the reflectors are located between theheating elements and the walls of the oven.

FIG. 7 represents a cross-sectional view through the oven 30. As thebottom of the receptacle is also constructed of open mesh-like material,the heat is permitted to penetrate all facets of the receptacle withmini mum interference. It will be seen that the view presented shows thethermoplastic bags in a partially softened condition and has alreadybegun to collapse towards the bottom of the receptacle. It will also benoted that the oven 30 has been modified to include a plurality of pins53 depending downwardly from the ceiling of the oven. The function ofthese pins is ingenious. It will'be considered that the receptacle maybe filled to a point where the thermoplastic bags are overflowing abovethe brim of the receptacle. As stated heretofore the-bags are bulky dueto pockets of air. As i the oven 30 is lowered into position, the pins53 are arranged and constructed to push or mechanically assist incompressing the bags to a position below the edge of the receptacle. Forinstance, in the embodiment of FIG. 3 it will be seen that the ceilingof the oven does not possess compressing pins. However, as thereceptacle in the embodiments shown in FIG. 3 has top closure doors, thereceptacle may be filled to be above the top edge of the receptacle.While the top doors may not be closed due to the excess quantity of bagsthe weight of the oven on the doors combined with the weight of thedoors themselves will assist in compressing the bags down into thereceptacle. It is entirely possible that when an oven is employed havingthe downwardly depending pins 53, the doors at the top may be totallyomitted.

After bags have been melted and thereby compacted into a mass at thebottom of the receptacle, the oven is removed so that the receptacle maybe moved away and/or additional bags or thermoplastic film material maybe added thereto. This procedure may be accomplished as many times aspracticable until the receptacle is filled with a mass of thermoplasticmaterial. Gate 12 then provides access to the interior of the receptacleso thatthe now resultant mass of melted thermoplastic material may beremoved.

FIG. 8 illustrates another embodiment of the receptacle of the presentinvention. It will be seen that instead of providing agate 12, acompletely removable partition 60 is employed. The partition is retainedin place by a plurality of loops 61 on the sides thereof which arearranged and constructed to sit on complementary hooks 62 on the edgeside walls of the receptacle. In this embodiment the partition 60 isliftedoff to provide communication interiorly with respect to thereceptacle.

It will also be observed that the receptacle of FIG. 8

does not have the skids 14 as heretofore illustrated but ratherpossesses a plurality of casters 63 at the bottom corners of thereceptacle. In this embodiment the receptacle may be moved about asdesired without the necessity of employing a forklift truck, unless itbecomes too heavily laden. The casters are of a sufficient size toprovide adequate clearance for the tines of a forklift truck.

FIG. 9 depicts yet an additional embodiment of the type of receptacleapplicable to the present invention. By sloping the walls inwardlydownwardly, it is possible and desirable to nest the receptacles asshown.

The receptacle in FIG. 10 is still another embodiment. It will be notedtherefrom that only a single door 64 is used as it is of a size to coverthe entire opening of the receptacle. Additionally, the receptacle is onmetal frame skids 65 as opposed to the wood skids 14 commonly used inconnection with pallet-like structures.

In another embodiment as disclosed by FIGS. 11 and 12, the receptacle isconstructed from a foldable blank shown, generally, by reference numeral66. The receptacle may be easily fabricated by properly folding theblank. The resultant receptacle may be held together by suitable meanssuch as metal clips applied to the corners. Those skilled in the artwill, of course, visualize means for adequately securing the parts. H0.12 is clearly illustrative of a manner of stacking a plurality of blanksprior to use. While a completed receptacle will consume considerablevolume, it will be readily appreciated that such is not the case whenthe receptacles are stored in a blank condition and stacked in thefashion of FIG. 12. y

lt will be seen that the invention here described in considerable detailprovides a highly acceptable means and method for the disposal andrecycling of waste thermoplastic material.

What is claimed is:

l. A method for compacting bulky convoluted air pocket containingthermoplastic film material comprising establishing a hot zone of atleast 240 F. consisting of a confined heated body of air, introducing aquantity of the said film material into a receptacle having a pluralityof openings along all of its surfaces, then relatively moving said hotzone and said receptacle whereby said receptacle is introduced into saidhot zone and the contents therein are subjected to the said body ofheated air in said hot zone, maintaining said receptacle in said hotzone for a period of time sufficient to fuse said film material into amass, thereafter separating said hot zone and said receptacle.

2. The method of claim 1 wherein the film material comprisesthermoplastic film material in the form of waste bags.

3. The method of claim 2 wherein the additional step is included ofadding additional film material to .the mass in the receptacle and againsubjecting the receptacle to said hot zone.

4. The method of claim 2 wherein the bags are subjected to mechanicalcompression while the receptacle is in the hot zone.

1. A method for compacting bulky convoluted air pocket containingthermoplastic film material comprising establishing a hot zone of atleast 240* F. consisting of a confined heated body of air, introducing aquantity of the said film material into a receptacle having a pluralityof openings along all of its surfaces, then relatively moving said hotzone and said receptacle whereby said receptacle is introduced into saidhot zone and the contents therein are subjected to the said body ofheated air in said hot zone, maintaining said receptacle in said hotzone for a period of time sufficient to fuse said film material into amass, thereafter separating said hot zone and said receptacle.
 2. Themethod of claim 1 wherein the film material comprises thermoplastic filmmaterial in the form of waste bags.
 3. The method of claim 2 wherein theadditional step is included of adding additional film material to themass in the receptacle and again subjecting the receptacle to said hotzone.
 4. The method of claim 2 wherein the bags are subjected tomechanical compression while the receptacle is in the hot zone.